Understanding and supporting change in health systems using the strategic action fields framework: the availability and origin of sources of authority

Policy-driven change in public service systems is difficult to implement. We focus upon ‘sources of authority’, which figure within the Strategic Action Fields Framework (SAFF) as resources mobilized by socially skilled actors to catalyse and sustain change. Drawing on qualitative case studies evaluating a large-scale policy-driven change in the English NHS, the Vanguard New Care Models programme, we (1) expand the definitions of ‘sources of authority’ and (2) argue that ‘sources of authority’ vary across two intersecting dimensions. This expands the utility of the SAFF beyond understanding and evaluating policy impact, and offers practical opportunities for achieving change.